<users>
     <user>
     <fullname>PC1</fullname>
     <flooor>4</floor
     </user>
     <user>
     <fullname>PC2</fullname>
     <flooor>3</floor
     </user>
</users>

<?php
 
$users = new DOMDocument();
$users->load("officedata.xml");
$suser = simplexml_load_file("officedata.xml");
$count = 0;
 
foreach($suser->user as $user) {
 
     if ($user['fullname'] == "PC1") {
    $users->documentElement->removeChild($users-       documentElement->childNodes->item($count));
    $count--;
    }
    $count++
}
$users->save("officedata.xml");
 
?>

$users = new DOMDocument();
$users->load("officedata.xml");
 
$suser = simplexml_load_file("officedata.xml");
$count = 0;
 
$user = $users->getElementsByTagName("user");
 
foreach($user as $value)
{
   $count++;
   $tasks = $value->getElementsByTagName("fullname");
   $task  = $tasks->item(0)->nodeValue;
 
   if ($task == "PC1") {
    $users->documentElement->removeChild($users->documentElement->childNodes->item($count));
   }
}
 
$users->save("officedata.xml");
?>